Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000 FXUS61 KRNK 221131 AFDRNK AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 731 AM EDT TUE JUL 22 2014 .SYNOPSIS... UPPER TROUGH OVER THE GULF COAST STATES RETROGRADES TOWARD LOUISIANA AND TEXAS THROUGH WEDNESDAY. A COLD FRONT WILL BE ARRIVING THURSDAY FROM THE NORTHWEST...THEN EXITING BY THURSDAY NIGHT. HIGH PRESSURE BUILDS IN FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 330 AM EDT TUESDAY... GOING TO SEE HIGH PRESSURE AT THE SFC WEAKEN TODAY INTO TONIGHT AS IT PUSHES SOUTH OVER THE SOUTHERN APPALACHIANS. UPPER LEVEL TROUGH IS GOING TO RETROGRADE TOWARD THE LOUISIANA COAST BY TONIGHT AS WELL...AS A NORTHERN STREAM TROUGH STARTS TO DIG SOUTHEAST INTO THE GREAT LAKES...WITH UPPER RIDGING EXTENDING WWD FROM THE SOUTHEAST COAST. FOR US...THE MODELS CONTINUE TO ADVERTISE DIURNALLY DRIVEN CONVECTION...WITH NO REAL FOCUS ASIDE FROM DIFFERENTIAL HEATING AND SOME LOW LVL UPSLOPE CONVERGENCE IN THE SRN MTNS. BETTER LIFT EXPECTED TO STAY WEST OF THE APPALACHIANS THIS AFTERNOON. PWATS REMAIN HIGH GIVEN WEAK FLOW...THE SLOW MOVING STORMS COULD PRODUCE WELL OVER AN INCH OF RAIN IN A SHORT AMOUNT OF TIME. THUNDERSTORM THREAT WILL BE THERE...BUT SOUNDING SUGGEST NO ROBUST CAPE...SO NOT REALLY SEEING ANY STRONG/SVR STORM THREAT AT THIS TIME. TONIGHT...THE SHOWERS AND ISOLATED STORMS WEAKEN/DISSIPATE BY MIDNIGHT. ISOLATED SHOWERS MAY LINGER OVERNIGHT...GIVEN PLENTIFUL MOISTURE IN THE LOW LVLS INTERACTING WITH ANY OUTFLOW BOUNDARIES. STILL LOOKS LIKE A LITTLE MORE SUN ESPECIALLY IN THE WEST TODAY WITH SKIES STAYING PARTLY SUNNY-OVC EAST OF THE BLUE RIDGE. HIGHS TODAY WILL BE SIMILAR TO A FEW DEGREES WARMER THAN MONDAY...DEPENDING ON EXTENT OF SUN. WILL BE REALLY HUMID...WHICH WITH HIGHS IN THE MID TO UPPER 80S OUT EAST SHOULD DRIVE HEAT INDICES INTO THE LOWER TO MID 90S. TONIGHTS LOWS REMAIN MUGGY/WARM WITH MID 60S TO AROUND 70. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... AS OF 345 AM EDT TUESDAY... WILL START WEDNESDAY MORNING OFF WITH ONLY ISOLATED SHOWER ACTIVITY UNDER LIGHT SOUTHWEST TO WESTERLY WIND FLOW AS A SURFACE TROUGH DEVELOPS EAST OF THE BLUE RIDGE. COVERAGE OF SHOWERS AND THUNDERSTORMS WILL INCREASE DURING THE AFTERNOON HOWEVER AS A COLD FRONT APPROACHES FROM THE OHIO RIVER VALLEY. BEST INSTABILITY WILL BE FOUND ACROSS THE MOUNTAINS...WHERE CAPES WILL REACH INTO THE 1500- 2000 J/KG RANGE BY EARLY EVENING AS AFTERNOON HIGHS REACH INTO THE MID 80S WEST TO THE LOW 90S EAST. BELIEVE SHOWERS AND STORMS WILL DEVELOP ACROSS THE MOUNTAINS BY EARLY AFTERNOON AS PULSE HIT AND MISS ACTIVITY...POSSIBLY MERGING INTO MORE ORGANIZED LINE SEGMENTS ACROSS THE PIEDMONT DURING THE EVENING. WITH STRONG HEATING AND ABUNDANT DRY AIR IN THE MID LEVELS...EXPECT A FEW STORMS TO BECOME SEVERE DURING LATE AFTERNOON AND EVENING...PRODUCING STRONG WINDS AS THE MAIN THREAT...IN ADDITION TO HAIL AND LOCALLY HEAVY RAIN. STORMS WILL WEAK DURING LATE EVENING...BUT EXPECT WE WILL STILL HAVE SHOWERS PASSING ACROSS THE AREA WEDNESDAY NIGHT AS THE COLD FRONT ARRIVES ON OUR DOORSTEP. MODELS ARE IN DECENT AGREEMENT THAT THE COLD FRONT WILL ENTER OUR SOUTHEAST WEST VIRGINIA COUNTIES LATE MORNING/EARLY AFTERNOON ON THURSDAY...AND CONTINUE EAST THROUGH THE DAY. HOWEVER...WITH AN UPPER LEVEL TROUGH SHIFTING EAST OF OUR AREA AND INCREASED CLOUD COVER TO LIMIT HEATING...ATMOSPHERIC INSTABILITY WILL NOT BE AS INTENSE. EXPECT MORE IN THE WAY OF SHOWER ACTIVITY ON THURSDAY WITH ONLY WIDELY SCATTERED THUNDERSTORMS IN THE MIX...MAINLY ACROSS THE PIEDMONT. HIGHS WILL REACH INTO THE UPPER 70S ACROSS THE MOUNTAINS...WHILE WE MAY TOUCH 90 ACROSS THE SOUTHSIDE BEFORE THE COLD FRONT MOVES ACROSS. WEAK HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT...AND WILL BE IN CONTROL OF OUR WEATHER PATTERN FOR FRIDAY. AS SUCH...EXPECT A LIGHT NORTHERLY FLOW THAT WILL CARRY DRIER AIR INTO THE REGION FROM THE GREAT LAKES. AFTERNOON HIGHS WILL VARY FROM THE MID 70S WEST TO THE MID 80S EAST. MAY SEE THUNDERSTORMS RETURN TO THE AREA LATE FRIDAY NIGHT AS WINDS ALOFT SHIFT NORTHWESTERLY...ALLOWING UPPER LEVEL DISTURBANCES TO APPROACH THE AREA FROM THE MIDWEST. && .LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 445 PM EDT MONDAY... FOR THE WEEKEND AND INTO EARLY NEXT WEEK...THE AREA REMAINS VULNERABLE TO NW FLOW DISTURBANCES TRACKING AROUND THE LARGE WESTERN/CENTRAL CONUS UPPER RIDGE. THERE ARE SEVERAL SUCH STRONG DISTURBANCES NOTED IN THE MODELS DURING THIS TIME FRAME...THE MOST NOTABLE ON SUN...THAT COULD BRING THUNDERSTORMS BACK INTO THE AREA. HAVE RETAINED EXISTING CHC POPS THAT WERE ADVERTISED WITH EARLIER FORECAST PACKAGES...BUT CLEARLY THESE COULD POTENTIALLY BECOME LIKELY AT SOME POINT AS THE DEVELOPMENT OF AN UPSTREAM MCS BECOMES MORE APPARENT. BY EARLY THE FOLLOWING WEEK...MODELS IN GOOD AGREEMENT ON THE UPPER TROUGH REAMPLIFYING ACROSS THE EASTERN CONUS...WHICH SHOULD KEEP CONDITIONS UNSETTLED WITH NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES WHILE THE EXTREME HEAT REMAINS WELL TO OUR WEST AND WELL AWAY FROM OUR PART OF THE COUNTRY. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 730 AM EDT TUESDAY... GETTING -DZ HERE AT BCB THIS MORNING. CIGS/VSBYS HAVE BEEN ERRATIC OVERNIGHT RANGING AT TIMES FROM LIFR TO VFR. THINK ANY FOG/SUB VFR CIGS WILL LIFT AROUND 14-16Z. STILL LOOKING AT HIT OR MISS SHRA/TSRA TODAY BUT BEST COVERAGE WILL BE IN THE DANVILLE AREA. KEPT VCTS AT ALL SITES BUT LYH/BLF. ANY CONVECTION WEAKENS/SUBSIDES AROUND 00Z/23...WITH FOG FORMATION LIKELY LATE EVENING INTO OVERNIGHT. THINK BCB/LWB WILL BE IFR OR WORSE BY THIS TIME TOMORROW. EXTENDED AVIATION DISCUSSION... UPPER TROUGH OVER THE GULF COAST RETROGRADES WESTWARD INTO WEDNESDAY BEFORE NORTHERN STREAM TROUGH AND COLD FRONT MOVE BY THURSDAY AND PICK IT UP. STILL LOOKS RATHER MOIST IN THE LOW LVLS AHEAD OF THE FRONT FOR AFTERNOON CONVECTION...SO MAINLY VFR AFTER MORNING LOW CLOUDS/FOG WEDNESDAY. BETTER THREAT OF SHRA/TSRA WITH THE FRONT THURSDAY. AIRMASS WILL DRY OUT BEHIND THE FRONT GOING INTO FRI-SAT. OVERALL EXPECT SUB VFR AT TIMES THU WITH SHRA/TSRA AND MAYBE SOME FOG THU NIGHT...FOLLOWED BY VFR FRI-SAT OUTSIDE OF ANY VALLEY FOG AT LWB/BCB EACH MORNING. && .EQUIPMENT... AS OF 100 AM EDT TUESDAY... KFCX RADAR REMAINS DOWN. PARTS TO ARRIVE LATER THIS MORNING WITH TECHNICIANS WORKING ON GETTING OUR RADAR OPERATIONAL BY TUESDAY AFTERNOON. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...WP NEAR TERM...WP SHORT TERM...NF LONG TERM...PM/RAB AVIATION...WP EQUIPMENT...WP

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